Methicillin-resistant Staphylococcus aureus: acquisition and risk of death in patients in the intensive care unit

OBJECTIVE To evaluate the risk of patients in intensive care units (ICU) of becoming infected with methicillin-resistant Staphylococcus aureus (MRSA) and to assess the mortality during a six week follow-up period, compared with patients who developed methicillin-sensitive S. aureus (MSSA) infection. DESIGN Point prevalence survey. SETTING 1417 ICU in 17 Western European countries. SUBJECTS 10038 patients in ICU who were part in the EPIC (European Prevalence of Infection in Intensive Care) Study. MAIN OUTCOME MEASURES Prevalence of MRSA and MSSA ICU-acquired infections, risk factors, and mortality. RESULTS On the study day 21% of patients had ICU-acquired infections. The most commonly reported pathogen was Staphylococcus aureus (30%). Overall, 60% of strains of S. aureus were resistant to methicillin (with a wide intercountry variation). The most commonly reported MRSA infections were pneumonia and lower respiratory tract infections. The most important risk factor for MRSA was the length of stay in the ICU. MRSA infection reduced the chance of survival, particularly when it was found in lower respiratory tract infections: the risk of mortality was three times higher in patients with MRSA than in those with MSSA. CONCLUSION Patients in ICU are at high risk of becoming infected with MRSA. The longer they stay, the higher the risk. Patients with MRSA infections are less likely to survive than those with MSSA.